1. Field of the Invention
The present invention relates to a POS system mounted with price look-up (PLU) tables, and more particularly to a maintenance system, and a recording medium recording thereon a maintenance program, for a plurality of price look-up tables held by a plurality of POS apparatuses connected by a POS server and a LAN.
2. Description of the Related Art
A POS apparatus according to the prior art searches from PLU tables, either built into itself or provided externally, for a key value registered in advance data (including names and prices) on products, and registers their sales.
A system in which a plurality of such conventional POS apparatuses by a local area network (LAN) may be in one of the following three forms.
In a first form, each POS apparatus has PLU tables in which are stored all the PLU data; in a second form, only one POS apparatus (POS server apparatus) has PLU tables in which are stored all the PLU data while no other POS apparatus has PLU tables; and in a third form, a POS server apparatus has PLU tables in which are stored all the PLU data while other POS apparatuses have PLU tables in which are stored part of the PLU data.
Where maintenance of PLU tables (addition, updating and/or deletion of PLU data (including key values, product name and prices)) is to be accomplished in a system of the first form, a message that maintenance will be executed is successively notified from one apparatus (POS server apparatus or POS apparatus) to all other POS apparatuses (if that maintenance is addition or updating of PLU data, the PLU data to be added or updated are successively transmitted), and each of the notified POS apparatuses maintains its own PLU tables.
Maintenance of PLU tables in a system of the second form is performed on PLU tables in the POS server apparatus.
Where maintenance of PLU tables is to be accomplished in a system of the third form, first the PLU tables of the POS server apparatus are maintained, after that a message that maintenance will be executed is successively notified to all other POS apparatuses (if that maintenance is addition or updating of PLU data, the PLU data to be added or updated are successively transmitted), and each of the notified POS apparatuses maintains its own PLU tables.
A system of the first form, since one apparatus successively notifies all other POS apparatuses that maintenance will be executed, if a considerably large number (e.g. hundreds) of POS apparatuses are connected to the LAN, there will arise a substantial lag in maintenance start time between the first notified POS apparatus and the last notified POS apparatus. Thus, there may arise a problem that, depending on the timing of accessing the PLU tables, the PLU data registered in the PLU tables differ between the POS apparatus whose maintenance was first started and another POS apparatus whose maintenance was later started, or the PLU data to be accessed are not yet registered in the POS apparatus whose maintenance was later started.
In the system of the second form, though only the PLU tables in the POS server apparatus need to be maintained, since only the POS server has all the PLU data, if the POS server apparatus fails, it will become impossible to access PLU tables in all the POS apparatuses and to perform sales-related duties.
The system of the third form, like the system of the first form, involves the problem that, if the POS server apparatus fails while it is transmitting PLU data to other POS apparatuses, the contents of PLU tables may become different among different POS apparatuses.
An object of the present invention is to enable, in a system wherein a POS server apparatus and a plurality of POS apparatuses are connected by a LAN, maintenance of PLU tables held by the POS apparatuses to be executed without time lags among the apparatuses.
Another object of the invention is to enable, in a system wherein a POS server apparatus and a plurality of POS apparatuses are connected by a LAN, even if the POS server apparatus fails, maintenance of other POS apparatuses to be continued and the identity of their contents to be secured.
A first maintenance system for a plurality of price look-up tables according to the invention consists of a POS server apparatus connected to a network and a plurality of POS apparatuses, wherein the POS server apparatus stores, in response to entry of PLU data, data consisting of a combination of revision history information on the pertinent PLU data and the revised data into a master PLU history management table, at the same time multicasts the data to all of the aforementioned POS apparatuses, and stores those PLU data into a master PLU table; and each of the plurality of POS apparatuses stores the data multicast from the POS server apparatus into a local PLU history management table and, at the same time, stores the PLU data contained in the pertinent data into a local PLU table.
A second maintenance system for a plurality of price look-up tables according to the invention derives from the first maintenance system for a plurality of price look-up tables, wherein the POS server apparatus, when a plurality of sets of PLU data have been entered collectively, uses for each set of PLU data the entry date and time of the pertinent PLU data, the total number of the plurality of sets of PLU data and the serial number of that particular set of PLU data out of all those sets of PLU data as the revision history information; uses the pertinent set of PLU data and the type of processing applicable to that set of PLU data as the revised set of data; after the storing of data combining together the pertinent revision history information and the pertinent revised data into the master PLU history management table, multicasts all the sets of data stored into the master PLU history management table to all of the aforementioned POS apparatuses and, at the same time, and stores the aforementioned plurality of PLU data into the master PLU table; and each of the aforementioned plurality of POS apparatuses stores the plurality of sets of data multicast from the POS server apparatus into the local PLU history management table; at the same time, references the serial number and the total number of the sets of PLU data included in the revision history information of each of the pertinent plurality of sets of data; and, if it is confirmed that there is nothing missing in the plurality of sets of data multicast from the POS server apparatus, causes the plurality of sets of data included in the revised data of each of the pertinent plurality of sets of data to be reflected in the local PLU table according to the type of processing for the pertinent set of PLU data.
A third maintenance system for a plurality of price look-up tables according to the invention derives from the second maintenance system for a plurality of price look-up tables, wherein each of the plurality of POS apparatuses, when power supply thereto is turned on, extracts the revision history information containing the latest entry date and time out of the plurality of sets of data stored in the local PLU history management table, and transmits it to the POS server apparatus; the POS server apparatus, if revision history information containing any newer entry date and time than the entry date and time of the revision history information transmitted from the POS apparatus is stored in the master PLU history management table, multicasts to all of the POS apparatuses data combining the pertinent revision history information and the revised data corresponding to that revision history information; and each of the plurality of POS apparatuses, if the data multicast from the POS server apparatus are not stored in its local PLU history management table, stores those data into the local PLU history management table, and the PLU data included in those data are caused to he reflected in the local PLU table according to the type of processing of those PLU data.
A fourth maintenance system for a plurality of price look-up tables according to the invention derives from the third maintenance system for a plurality of price look-up tables, wherein each of the plurality of POS apparatuses, when it has revised any PLU data on itself, prepares data combining the revision history information pertaining to the processing of that revision and the revised data including those PLU data; after storing them into the local PLU history management table, multicasts those data to the POS server apparatus and other POS apparatuses and, at the same time, causes the PLU data to be reflected in the local PLU table; the POS server apparatus stores the data multicast from the POS apparatuses into the master PLU history management table and, at the same time, causes the PLU data contained in those data to be reflected in the master PLU table according to the type of processing; and each of the plurality of POS apparatuses, if the data multicast thereto from the POS server apparatus are not stored in its local PLU history management table, stores the data into the local PLU history management table, and causes the PLU data contained in those data to be reflected in the local PLU table according to the type of processing of the PLU data.
A fifth maintenance system for a plurality of price look-up tables according to the invention derives from the fourth maintenance system for a plurality of price look-up tables, wherein the POS server apparatus, when power supply thereto is turned on, requests the plurality of POS apparatuses to transmit the revision history information stored in the respective local PLU history management tables; each of the plurality of POS apparatuses, in response to the request from the POS server apparatus, transmits the revision history information stored in the local PLU history management table thereof, to the POS server apparatus; the POS server apparatus, if it finds the entry date and time of the revision history information transmitted from any of the POS apparatuses newer than the revision history information stored in its master PLU history management table, requests that POS apparatus to transmit data combining the transmitted revision history information and revised data corresponding to the revision history information; each of the POS apparatuses, in response to the request from the POS server apparatus, reads those data out of its own local PLU history management table and transmits them to the POS server apparatus; and the POS server apparatus stores the data transmitted from the POS apparatus into the master PLU history management table and, at the same time, causes the PLU data contained in those data to be reflected in the master PLU table according to the type of processing of those PLU data.